The conventional circuit breaker uses a fuse between a switch and a circuit so that when the circuit breaker is overloaded, the fuse will first melt before damages occur. However, if the fuse is not properly installed or an improper fuse is used, the overload current cannot melt the fuse and a disaster can be caused. U.S. Pat. Nos. 5,262,748, 4,167,720, 4,937,548, 5,223,813, 5,451,729, and 5,558,211 unveil different types of circuit breakers, commonly including a complicated mechanism to drive the bimetallic plate that is expected to be deformed and bent when the circuit breaker is overloaded. Nevertheless, it is noted that the bimetallic plate may not be completely deformed as desired because it can not be freely deformed and is still in contact with the terminal. As a result sparks may be generated cause a disaster.
Therefore, it is desired to have a safety switch device that allows the bimetallic plate to be freely deformed when the switch device is overloaded thus to overcome the shortcomings of the conventional switch devices.